The sun rises over Krypton, a planet that we all already know isn’t going to make it past the opening credits of this series. Kara Zor-El introduces herself, her planet, and her little cousin and we see the struggle both she and her parents have with letting her go. Her mother tells her that Earth’s yellow sun will give her extraorindary powers, how she knows this doesn’t matter, but it’s in Kara’s transit off world that she gets knocked off course and into the elusive Phantom Zone where she tumbled for over two decades before finally landing on Earth. Though she was sent to protect her cousin, he doesn’t need it anymore, because he’s already grown into Superman. Old Supes takes Kara to a family of scientists, The Danvers, who previously helped him understand his own abilities.
Fast forward to another decade later, Kara just wants to fit in and works at Catco Worldwide Media in National City. There she works with one Winn Schott, who clearly fancies her in addition to reports of aliens, and underneath Cat Grant, the namesake for the company and a powerful media mogul in her own right. Cat tells Kara to prepare termination letters for some of the employees of the National City Tribune, a struggling paper recently purchased by Grant, and also to go see the new art director she just hired. Kara enters the office and finds the new hire, none other than Superman’s best pal, Jimmy Olsen. They talk about “The Big Man” himself, and Jimmy gives Kara a print of his Pulitzer Prize-winning photo of Superman.
That night, Kara’s sister Alex comes by her apartment to help her prepare for a date and listen to her vent about her day job, and clearly Kara wants to do something more with her life. Alex sends Kara out on her date in a blue outfit, it’s her color after all, and leaves for her flight to Geneva for work. Kara heads to her date, which goes poorly, but soon notices a news story about Flight 237 (a sly The Shining reference?) that is in distress over National City – naturally this is her sister’s flight. Kara runs out of the bar and tries her hand at flying, a task she hasn’t done in years, but eventually soars into the sky. Kara finds the plane, where she’s quickly spotted by her sister, and guides it from the underside through the opening in a city bridge (named for the late comic scribe Otto Binder, creator of Supergirl in addition to other key Superman elements such as Brainiac, Bizarro, and The Phantom Zone) and onto the water, saving everyone on board. As people begin to notice her and take her picture, she flies off into the air once again.
Back home, Kara watches news reports on her heroism, only to be shocked by some people that aren’t entirely thrilled with her. Right on cue, her sister arrives, worried that Kara has exposed herself to the world, but Kara says she didn’t travel all this way to be an assistant (both a narrative reference and a meta dig, because this character is clearly no sidekick). She feigns sleep to end their little tiff. The next morning, Kara acts normal at work, but Cat Grant is furious they don’t have any exclusive coverage of this new hero in town but is happy that she won’t have to sack all those employees from the Tribune now. When asked by Cat, Jimmy says he isn’t sure she has a connection to Superman, prompting a gulp from Kara. Winn briefly mentions that people won’t take this person seriously if she doesn’t have a costume, which leads Kara to bring him to the roof and tell him her secret – she’s the woman from the plane.
At an undisclosed diner, a man digs his fingers into the counter while watching a report on the female hero. He heads outside and to his gas tanker, climbing inside the tank to speak with a man on monitor. The trucker, Vartox, says everything was going to plan until the girl, clearly the daughter of Alura Zor-El, stopped it. Vartox picks up his big gnarly ax and says she’ll pay for this. Back at Kara’s apartment she tries on different outfits, and fighting crime in said outfits, before eventually settling on the look that we’ll be seeing her fly around in for the series. Winn, who helped with the costume design, notices an alarm for a fire downtown and Kara flies into action, only to be pelted with some darts, causing her to fall to the ground and be scooped up by mysterious men in uniforms.
Kara wakes up in a concrete room, strapped to a table with Kryptonie gauntlets. A man who introduces himself as Hank Henshaw (the villain Cyborg Superman in the pages of DC Comics) stands over her just as Kara’s sister Alex enters. They work for the Department of Extranormal Operations, monitoring alien presence and invasions on Earth, and they’ve known all about Kara since she first arrived, they even have her ship in the office. Henshaw reveals to Kara that when her ship came out of the Phantom Zone and toward Earth, she brought something with her, Fort Rozz, the prison held inside the PZ. As a result, some nasty alien criminals have been running around Earth for 13 years and they’re all preparing for something now. Kara wants to help, but both her sister and Director Henshaw tell her to let it go.
The next morning, Kara arrives at work to find that Cat Grant has christened her Supergirl,” a name she is first apprehensive about but comes around on after a near-firing. Jimmy enters the office mid-termination and saves Kara’s skin by presenting Cat with a photo that he gives credit to Kara for the first clear photo of Supergirl. As Kara and Jimmy leave Cat’s office, Vartox sends her a message via a wavelength only she can hear, demanding to fight her at the power plant. Kara flies to the location for the bout and takes some pretty strong hits from her new opponent, who taunts her about her mother before being scared away by Alex and the DEO’s attack helicopters.
They examine Kara’s injuries sustained from the fight, in particular from Vartox’s ax, and Alex reveals that she knew about Kara’s birth mother, which was one of the many reasons she didn’t want her to ever embrace her powers, which almost convinces Kara the world doesn’t need her. That night, Alex comes to talk to Kara and explains that she was never used to playing second fiddle before Kara arrived and that her existence was always a bit of a threat to her, but the world needs her, and her family needs her (not just her Earth family, her Kryptonian family) and presents Kara with a device from her crashed ship containing a message from her mother that her destiny is not tied to Kal-El, that she can choose her own path in life. Kara changes back into her uniform and heads back to the DEO base, prepared to fight Vartox.
Thanks to her injury from her ax, the DEO are able to track Vartox, which she does to an empty road outside of town. Kara lands in front of Vartox’s truck, causing him to fly from the windshield and much of it to explode. They fight to a stand still and just as it seems he has the upper hand, Kara lets lose her secret weapon, heat vision. By heating up Vartox’s ax, she’s able to make it explode and send him careening across the road. Vartox takes a piece of his own ax and taunts Kara with a warning about what is to come before killing himself with the shard. Back at the DEO base, Alex wonders if it was Kara that got her this job to begin with, and Henshaw says it was but that she earned her place there by being herself (get it? It’s the theme of the show).
Winn asks Kara about her fight in the desert the next morning, which he naturally read about on the alien hunting websites, and also drops a cute reference to the Super Friends. Kara runs into Jimmy, who makes it painfully obvious he knows her secret and asks to meet her on the roof. Up top, he reveals Superman told him her secret and pushed him toward his career path at National City. He tells her that the Big Man wanted her to choose this path for herself and he sent along a gift, the blanket he was wrapped in as a baby, which will make for an indestructible cape. Meanwhile, in an undisclosed location, the commander that communicated with Vartox earlier reports to “The General” about Kara’s acts on earth, prompting her to order her death, even if Kara is her niece.